In the field of composite explosives, one specific characteristic that has served as an impediment to widespread processing and production of conventional, and especially of new classes of explosives, is the limited number of neat high explosives that are able to meet the Bureau of Explosives requirements for handling and transporting. Consequently, various techniques, such as blending or coating the explosive with a phlegmatizing agent, are usually employed to overcome this limitation, but in general these techniques are themselves subject to other limitations. For example, coatings often (1) are cumbersome to apply, (2) are difficult to adapt to production of composite explosives because of incompatibility with other ingredients that are later blended with the desensitized explosive, (3) lower the detonation energy and detonation pressure of the explosive because an excessive quantity of phlegmatizing agent is often required for adequate desensitization, (4) do not permit adequate removal of water or other diluent from the as-received explosive because of inherent chemical or physical processing difficulties, and (5) introduce undesirable additional costs to the process. Specifically, as-received cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX) have been blended or coated with various wax-type phlegmatizing agents in explosive compositions, which include a range of concentrations of inert, non-reactive desensitizing waxes.
We have now discovered desensitized explosives that are able to meet the Bureau of Explosives requirements for handling and transporting, which also avert the usual limitations associated with conventionally desensitized explosives, by coating sensitive materials such as RDX and HMX with a phlegmatizing agent that has potentially chemically reactive groups, such that the phlegmatizing agent ultimately may become an integral part of a thermally stable, crosslinked polymeric structure, capable of being cast in place at mild, ambient temperature into any desired shape or mold. In addition, the desensitizing agent has specific characteristics such that it can easily be fabricated into a castable and curable composite explosive whose cure rate and flexibility can both be varied within a wide range by appropriate, readily made changes in the formulation. Moreover, the composite explosives that can be fabricated from such desensitized neat explosives exhibit very low degrees of shrinkage, have glass transition temperatures below -65.degree. F., have excellent thermal stability (gas evolution less than 2 cc/gram after 48 hours at 120.degree. C.), and demonstrate high detonation pressures and detonation energies. No known high explosive combines the characteristics of insensitivity and ability to meet Bureau of Explosives requirements for handling and shipping with the capacity for ready formulation into composite explosives that are compatible and exhibit all the aforementioned characteristics. Since there are current explosive applications that require many of the designated characteristics, and some applications that require all of them in a single composite explosive, the availability of desensitized, neat explosives which are amenable to fabrication into single composite explosives that achieve this combination of properties represents a distinctly new approach in the art of explosive compounding.